Fumaric acid stabilizer for single powder photographic developers



United States Patent FUMARIC ACID STABILIZER FOR SINGLE POW- DER PHOTOGRAPHIC DEVELOPERS Laurence G. Welliver, Binghamton, N.Y.

No Drawing. Application November 15, 1956 Serial No. 622,276

6 Claims. (Cl. 96-66) The present invention relates to single powder photographic developers in which all of the essential ingredients of the developer are intimately admixed in dry powder form and, more particularly, to the use of fumaric acid as an acidic stabilizer for such developers. 7

Single powder photographic developers contain as their essential ingredients one or more organic developing agents, an alkali, a preservative and an anti-foggant. Under ordinary conditions of mixing and storage, such dry developers undergo decompositionreactions which adversely aifect the photographic activity of the developers.

The art has been cognizant of this phenomenon, and in an efiort to avoid it, has provided for the presence in such developers of an acid stabilizer such as phthalic acid, boric anhydride, metaboric acid and the like. These compounds, as a general rule, are capable of forming anhydrides and a theory still unproven has been developed that the eifectiveness of the stabilizer depends upon its ability to form an anhydride. In any case, regardless of the theory, it is a fact that the various acid stabilizers which have heretofore been used do not promote the keeping qualities of the developers to an optimum extent, as is evident by the fact that developers containing the same may discolor within a period of two to three months.

It has now been discovered, and rather unexpectedly so, that greater keeping qualities are imparted to single powder photographic developers if fumaric acid be used as the stabilizer. The fact that this compound is able to enhance the keeping qualities to a greater degree than the usual acid stabilizers comes as a surprise when it is considered that it cannot form an anhydride and, as previously noted, most of the previously used effective stabilizers are capable of forming anhydrides.

Single powder photographic developers containing fumaric acid as the stabilizer, preferably with an alkali metal metabisulfite such as sodium or potassium metabisulfite, constitute the purposes and objects of the present invention.

The developers contemplated herein contain as their essential components an organic silver halide developing agent, an alkali, a preservative, an anti-fogging agent, an alkali metal metabisulfite and furnaric acid as the acid stabilizer. Developers with these components which we have found to possess unusual stability during mixing and storage may be compounded in the following proportions, it being understood that the resulting dry powder is to be used to make a liter of developing solution:

If it be desired, the developer may also contain, and preferably does contain, an alkali metal polyphosphate such as sodium hexametaphosphate, potassium hexameta- 2,891,861 Patented June23,. 1959 phosphate and the like. This component is tobe used in an amount of from 1 to 5 parts.

The photographic silver halide developing agent may be any of those previously mentioned and it may be used alone or in admixture with other developing agents. Typically, I may use a mixture of N-methyl-p-aminophenol sulfate and hydroquinone, N-methyl-p-aminophenol sulfate and l-phenyl-3-pyrazolidone (phenidone), phenidone and hydroquinone or phenidone, N-methyl-paminophenol sulfate and hydroquinone.

The preservative is usually sodium sulfite generally in the anhydrous condition and the anti-fogging agent is potassium bromide. The alkali may be any of-thoseused in compounding photographic developers, such assodium carbonate, sodium tetraborate or the like;

In compounding the aforesaid developing mixtures, one may proceed by first mixing the alkali, alkali metal metabisulfite and fumaric acid, blending this'mixture thoroughly, say, for ten minutes, in a cone blender and then adding the organic developing agent, preservative and anti-foggant and blending thoroughly as above;

The use of fumaric acid as the stabilizer is not only recommended because of its effectiveness but, in addition, because of its cheapness when compared to other acid stabilizers such as phthalic acid and the like presently employed.

The following examples will serve to illustrate my invention, the parts being by weight, it being understood that the invention is not restricted thereto.

Example I Parts Sodium carbonate monohydrate 79 Potassium metabisulfite ll Fumaric acid 1.9 N-methyl-p-aminophenol sulfate 4.2 Sodium sulfite 31.5 Hydroquinone 10.5 Potassium bromide .79

Example II Parts Sodium hexametaphosphate 3 Ethylenediamine tetra acetic acid 1 Potassium metabisulfite 11 Fumaric acid 1.9 Phenidone .25 N-methyl-p-aminophenol sulfate 3 Sodium sulfite 31.5 Hydroquinone 10.5 Potassium bromide 1 Example [II Parts Sodium hexametaphosphate 3 Sodium carbonate monohydrate 79 Potassium metabisulfite 11 Fumaric acid 1.9 N-methyl-p-aminophenol sulfate 4.2 Sodium sulfite 31.5 Hydroquinone 10.5 Potassium bromide .9

The quantity of the developer represented by the above formulae is to be dissolved in water to make one liter of developing solution.

The importance of the present invention is demonstrated by the following tests conducted with the powder of Example II, on the one hand, and with a powder compounded in exactly the same fashion as that of Example II but while using 1.0 parts of phthalic acid in lieu of fumaric acid, on the other hand.

Samples of the two powders were placed in low humidity (about 10%) and high humidity (about ovens at 120 F. After one-week storage at low humidity, the powder blended with phthalic acid was slightly discolored to a light brown color, while that compounded with fumaric acid remained white. After 24-hour storage at high humidity, the powder blended with phthalic acid was badly discolored to a dark brown color, while that compounded with fumaric acid was substantially white.

Modifications of the invention will occur to persons skilled in the art. I, therefore, do not intend to be limited in the patent granted except as necessitated by the appended claims.

I claim:

1. A single powder photographic developer containing an organic silver halide developing agent selected from the class consisting of hydroquinone, N-methyl-p-aminophenolsulfate, 1-phenyl-3-pyrazolidone and mixtures thereof, an alkali, sodium sulfite as a preservative, potassium bromide as an antifogging agent and fumaric acid as an acidic stabilizer for the developer.

2. A single powder photographic developer containing an organic silver halide developing agent selected from the class consisting of hydroquinone, N-methyl-p-aminophenolsulfate, 1-phenyl-3-pyrazolidone and mixtures thereof, an alkali, sodium sulfite as a preservative, potassium bromide as an antifogging agent, fumaric acid as an acidic stabilizer and an alkali metal metabisulfite.

3. The composition as defined in claim 2 wherein the quantity of fumaric acid ranges from .5 to 12 parts by weight and the quantity of the alkali metal metabisulfite amounts to 2 to 12 parts by weight per liter of developing solution.

3-pyrazolidone and mixtures thereof 4 to 15 Alkali 5 to Sodium sulfite 30 to Potassium bromide .5 to 2 Fumaric acid (acid stabilizer) .5 to 12 Alkali metal metabisulfite 2 to 12 5. The composition as defined in claim 4 wherein the composition contains from 1 to 5 parts of an alkali metal polyphosphate.

6. The composition as defined in claim 4 wherein the organic silver halide developing agent is a mixture of N-methyl-p-arninophenol sulfate and hydroquinone, the alkali is sodium carbonate, and the alkali metal metabisulfite is potassium metabisulfite.

References Cited in the file of this patent UNITED STATES PATENTS 2,374,921 Bunting May 1, 1945 FOREIGN PATENTS 826,812 France Jan. 12, 1938 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent Non 2,891,861 June 23, 1959 Laurence Go Welliver It is hereby certified that error appears in the-printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 69, for "1,0 parts" read 1.9 parts e Signed and sealed this 3rd day of November 1959.,

(SEAL) Attest:

KARL H AXLINE ROBERT C. WATSQN Attesting Officer Commissioner of Patents 

1. A SINGLE POWDER PHOTOGRAPHIC DEVELOPER CONTAINING AN ORGANIC SILVER DEVELOPING AGENT SELECTED FROM THE CLASS CONSISTING OF HYDROQUINONE, N-METHYL-P-AMINOPHENOLSULFATE, 1-PHENYL-3-PYRAZOLIDONE AND MIXTURES THEREOF, AN ALKALI, SODIUM SULFITE AS A PRESERVATIVE, POTASSIUM BROMIDE AS AN ANTIFOGGING AGENT AND FUMARIC ACID AS AN ACIDIC STABILIZER FOR THE DEVELOPER. 